Conventionally, as a large volume data recording medium, a read only medium which is called a CD-ROM (Compact Disc-Read Only Memory) is available. There is available a write-once type disc-like recording medium called Compact Disc-Recordable (CD-R) in which data can be recorded only once by forming a recording layer on the CD-ROM.
This CD-R can be played back by using a conventional CD-ROM drive so that all the data is recorded and prepared, for example, on a hard disc with the result that the CD-R in which writing is completed can be used as a CD (Compact Disc) by writing all the data in the CD-R.
By the way, since the CD-R having such a constitution can be written only once, it is difficult to rewrite the data in an area where data is written once in the same area so that it is difficult to use the CD-R as a rewritable recording medium like a so-called floppy disc.
The present invention has been made in view of the aforementioned point, and the invention is intended to provide an information processor and a method of information processing wherein the write-once type recording medium can be used in such a manner that the medium can serve as a rewritable recording medium.